1. Field of the Invention
The present invention generally relates to fluid pumps of the type in which a flexible tube is progressively distorted in order to produce a pumping action; that is, it relates to peristaltic pumps. More particularly, it relates to a novel pump of the peristaltic type which provides improved operating versatility, reliability, and life.
2. Description of the Prior Art
Peristaltic pumps are designed so that a hose or tube containing a fluid to be conveyed is sequentially squeezed by a series of mechanical fingers or cam surfaces arranged along a section of hose or tube. The following patents show prior art designs.
U.S. Pat. No. 2,877,714 to Sorg et al. shows a variable displacement tubing pump. FIGS. 6 and 7 show the tubing being pressed against itself for peristaltic pumping.
U.S. Pat. No. 3,427,986 to Corneil shows a fluid pump with controlled variable flow. FIG. 7 shows distortion of the tube against itself. Provision is made for regulating the degree of distortion in order to control the flow.
U.S. Pat. No. 3,609,069 to Martinelli shows a peristaltic pump for conveying liquids in a chemical apparatus. The drawing figure shows a series of plungers for squeezing the hose 2 against a bed 3 to move the liquid.
U.S. Pat. No. 3,981,633 to Wall shows a pump having a cylindrical tube within the hose. Progression of the fluid is achieved by a wave-like motion imparted on the hose. FIGS. 4a and 4b show the hose being pressed against the cylinder but not against itself.
U.S. Pat. No. 4,199,307 to Tassawalla shows a medical infusion pump which uses plungers that press against sleeve portions.
U.S. Pat. No. 4,302,164 to Manella shows a peristaltic pump which compresses the tube in two directions. FIG. 4 shows the hose flattened horizontally and then flattened vertically.
U.S. Pat. No. 4,373,525 to Kobayashi shows the use of a sensor to monitor the internal pressure of the fluid-infusion tube. Monitoring the internal pressure can serve to detect an occluding particle.
U.S. Pat. No. 4,561,830 to Bradley shows a linear peristaltic pump which uses cam actuated fingers to squeeze the fluid tube.
U.S. Pat. No. 4,671,792 to Bosanyi shows a pressure regulating peristaltic pump wherein a moveable platen positioned on a compression pad can be regulated in order to control fluid pressure at the outlet end of the hose.
U.S. Pat. No. 4,725,205 to Cannon et al. shows a peristaltic pump with cam action compensation that limits the force the peristaltic mechanism can exert against the tube.
U.S. Pat. No. 4,781,548 to Alderson shows an infusion pump with a conduit integral with a sturdier section.
It will be appreciated that the use of fingers or cam surfaces in prior art peristaltic pumps tend to stress the tube so that the pumps have a short operating life. Further, these prior designs are not well suited for use with a variety of pumped materials, such as for example slurries and other "lumpy" materials. Finally, these prior art peristaltic pumps are not readily adaptable to provide a range of volume-pressure outputs or reversible flow operation, or mixing applications.